1. Field of the Invention
The present invention concerns a signature deceleration device for delivery units which deliver flat products, such as a folding apparatus or the like.
2. Description of Related Art
U.S. Pat. No. 3,162,438 discloses a high-speed document stacking system. A pair of discs, each having a plurality of arcuate slots, is mounted on a common axis of rotation with the pairs of said slots being in alignment. A pair of conveyor belts terminate within a perimeter of said discs for delivering documents into the slots. A pair of guides are arranged between the discs for guiding the documents into the slots and a pair of stripper bars extend between the discs to the region of the inner extremities of the slots. The stripper bars will strip the documents from the slots in the discs.
U.S. Pat. No. 4,834,361 discloses a vane wheel as a lay-out device for printed products. The vane wheel device comprises a vane wheel including a shaft and a plurality of thin vane star discs fixedly mounted on the shaft in a lamellar fashion at a distance from one another. A band supply unit is associated with the vane wheel for supplying printed products to the latter, and a plurality of stationary blowing air nozzles are provided, each associated with a respective one of the vane star discs of the vane wheel. The direction and intensity of a blowing air stream from the blowing air nozzles influences the friction between the printing product falling into one vane and an outer side of another vane which is arranged behind the one vane. The vane star discs, the band supply unit and the blowing air nozzles are arranged in their positions relative to one another, so that the printing product, before its rear edge is ejected from the band supply unit, is blockable by the one vane which receives the printing product from the blowing air stream of the blowing air nozzles. While the printed product's rear edge is ejected, approximately one half of its length is received in the one vane and after ejection of its rear edge, it is braked by the streams of blowing air from the blowing air nozzles. A stripper associated with the vane star discs of the vane wheel and formed as a rack being adjustably mounted is engageable in intermediate spaces between the vane star discs. Through a pressure-air conduit, pressure is supplied to the blowing air nozzles, the pressure being controllable in dependence of a respective machine speed. The vane star discs have a shape which is optimal for braking during receiving the printed products in the vane star discs and for acceleration of the printed product during stripping-off by the stripper.
U.S. Pat. No. 4,886,264 discloses a method and an apparatus for receiving printed products from a rotary driven bucket wheel of a printing press. An outfeed conveyor is arranged beneath a rotary bucket wheel driven to rotate in a predetermined rotational direction. A belt conveyor is arranged downstream and a product entrainment arrangement is arranged upstream of the outfeed conveyor. An endless revolving belt is guided around belt rolls of the outfeed conveyor, and the printed products come to lie thereon in an imbricated formation. Entrainment elements of the product entrainment arrangement stuff the printed products completely into the pockets of a bucket wheel. Upon ejection of the printed products out of the bucket wheel, they are fixedly clamped at their trailing edges between a support element and extensions or cantilever arms of the entrainment elements, until the entrainment elements have passed the support element and thus, an intersection location between the entrainment elements and the support element. The resiliently arranged extensions of the entrainment elements are pivoted by the support element in a predetermined direction, such as clockwise, so that the printed products are cyclically released. There is thus formed an imbricated formation of printed products within which all printed products are aligned, and there can be maintained a substantially constant mutual spacing between the individual products.
U.S. Pat. No. 4,971,303 shows a paddle wheel distributor system for printed products. In order to provide for gentle braking by braking fingers located in axial slots between paddle wheel vanes or blades of paddle wheels, the braking fingers have an outer contour which is shaped and dimensioned, at least in the inlet region towards gaps, so that the printed products form an intersection angle which is defined by an axial projection between the contour of the braking fingers and an adjacent inner surface of a vane or a blade and continuously increases during rotation of the paddle wheel vanes or discs to define effective gaps of continuously decreasing width during rotation of the paddle wheel vanes.
The position of the fingers is adjustable along a predetermined direction by an electrical closed-loop positioning system which receives input signals representative of thickness of products and machine speed and, also emergency control signals to control the position of the fingers with respect to the vanes or blades. Emergency control signals cause withdrawal of the blades to a maximum effective gap position, for example, when tearing-off supply belts; increased braking by the fingers with a narrowed gap at different axial positions can be applied, in order to overcome skewing of incoming or delivered products.
Current device units suffer from an abrupt impact of stripping devices when stripping signatures from delivery units, such as delivery fans. At higher speeds, this sudden impact can cause leading-edge damage, such as the forming of dents. The arrangement of respective fan wheels in a staggered formation has resulted in an acceptable slowdown of signatures, but greater forces are then required to strip the product from the fan wheel pockets. This can, in turn, result in damage of the signature's leading edge. Other attempts to eliminate deficiencies of delivery units resulted in the use of secondary impacts as disclosed in U.S. Pat. No. 5,180,160, the reduction of silicone to increase friction, or the use of narrow pockets.